1. Technical Field
The present invention relates to an actuator, a liquid droplet ejecting head, a method of manufacturing the actuator and the liquid droplet ejecting head, and a liquid droplet ejecting apparatus.
2. Related Art
In a liquid droplet ejecting apparatus such as an ink jet printer which can be used, for example, in an image recording apparatus, a display manufacturing apparatus, or the like, it is known that an actuator having a piezoelectric device is used in a liquid droplet ejecting head for ejecting liquid droplets such as ink. In such an actuator, volume in a pressure chamber can be changed, for example, by deforming a substrate such as a vibration plate, which is formed below the piezoelectric device, by deforming a piezoelectric body of the piezoelectric device by application of a voltage such as a driving signal. Accordingly, the liquid droplet ejecting head can eject liquid droplets, such as ink supplied into the pressure chamber, from a nozzle orifice.
In such an actuator, a common upper electrode structure is known in which a plurality of piezoelectric bodies of the piezoelectric device is formed and an electrode (hereinafter also referred to as an “upper electrode”) which covers the piezoelectric bodies is formed so as to continuously cover the plurality of piezoelectric bodies (JP-A-2009-172878). In an actuator having the common upper electrode structure, compared to an electrode (hereinafter also referred to as a “lower electrode”) which is covered by the piezoelectric body, the upper electrode needs to function as an electrode common to a plurality of piezoelectric devices and there is a need for a larger current to flow through a lead wiring thereof than in a lead wiring of the lower electrode. Therefore, the lead wiring of the upper electrode requires high reliability.